Compensated induction motor for single or polyphase alternating current



April 24, 1928.

F. KADE COMPENSATED INDUCTION MOTOR FOR SINGLE OR POLYPHASE ALTERNATING CURRENT Filed June 2 1925 Jn Veh tor: flies/rich Kaela .10 provided Patented Apr. 24, 1928.

UNITED. STATES PATENT OFFICE.

FRIEDRICH KADE, OEKIEL, GERMANY, ASSIGNOR T0 DEUTSCHE WERKE KIEL AK- TIENGESELLSCH-AFT, OF KIEL, GERM ANY, A CORPORATION OF GERMANY.

COMPENSATED INDUCTION MOTOR FOR SINGLE OR POLYIPHASE ALTERNATING CURRENT.

Application fled June 20,

The subject of 1Patent application Serial N 0. 702,158 filed arch 28th, 1924, is a compensated induction motor having on the stator a winding adapted tobe connected with the mains and an auxiliarywinding, and on the rotor a polyphase exciting winding adapted to be connected with the auxiliary stator winding across a commutator, a winding which carries the working current with short-circuiting contacts and an auxiliary squirrel cage winding for startin the motor.

his squirrel cage winding is dimensioned from the point of view that a sufiicientl strong starting torque is produced in order to secure the starting of the motor. It is, however, important that the current impulse which the motor takes up from the mains does not exceed a certain value, and in view of this latter condition it is necessary to give the starting winding a large electrical resistance. If a motor designed from this aspect is started under load by means of the squirrel cage winding only a limited starting speed is attained, which is the lower, the greater the counter-torque of the shaft. After the motor has been started, the exciting ourrent'must be closed. The current impulse hereby set up is the greater the a lower the starting speed of the motor. This current impulse can readily assume a disagreeable value.

The present invention enables this disad- Vantage to be overcome. According to the invention after starting the motor not all the phases of the exciting circuitare at once closed, but only one or two phases of the auxiliary stator winding are connected with the commutator winding, the whole of the phases being connected upon the next following switch operation. In this manner a substantial reduction of the current impulse is efiected, so that the starting of the motor is not so disadvantageous to the mains.

e accompanying drawing illustrates dia ammatically b way of example a met 0d of carrying t e The main winding a adapted to be connected to the mains by switch-e and the auxiliary winding 0 are arranged on the stator. The

, winding 0 is to be connected by. switch 8,

invention into eifect.

1925, Serial N0. 38,578, and in Germany June 25, 1924.

with the exciting winding (not shown) of the rotor in the usual way across'a commutator d. In addition tothe exciting winding a working winding 6 is mounted on the rotor which can be short-circuited by the switchs The auxiliary squirrel cage winding is indicated by g. Th

are rigidly connected together e. g. by means of a controller as diagrammatically shown in Fig. 2. The switch 8 is so arranged and adjusted that upon switching over from the first switch position into the second only one or twophases of the winding 0 are cony nected to the commuted exciting winding,

which is effected for example by making the contacts of switch 3 of unequal length.

With the switch means shown in the drawing the switch operations upon actuating the positively coupled switches s s and s, are as follows :During the switching-in operation the stator winding a is first connected to the mains by the switch s (1st .step), whereupon the longer arms of switch 8, connects a single or double phase of the auxiliar winding 0 with the commuted exciting win ing (2nd. step). Upon further operation of the switch, the shorter arm of the switch 8, connects the auxiliary winding 0 with the commutator exciting winding in its full number of phases (3rd step). The final switch operation then closes the switch 8, whereby the working winding 12 of the rotor is totally closed.

I claim 1. A. compensated induction motor, having a main stator winding adapted to. be connected with the mains, a polyp ase auxiliary stator winding, commutator adapted to be connected with said auxiliary stator winding, a polyphase commutatorwinding, said commutator winding and 'said auxiliary stator winding forming the exciting circuit of the motor, a working winding on the rotor provided with short-circuiti'ng contacts, an auxiliary sqlulilrrel cage startlng winding, and contro g means adapted to successively connect the several phases of the said exciting circuit.

2. A compensated induction motor, having a main stator winding adapted to be connected with the mains, a polyphase auxa -commutator, brushes on the e switches 8,, s and s iliary stator winding, a commutator, brushes short-circuiting contacts, an auxiliary squiron the commutator adapted to be connected rel cage starting winding, and controlling with said auxiliary stator winding, a polymeans adapted to successively connect the -10 phase commutator winding, said commutator several phasesof said exciting circuit after 5 winding and said auxiliary stator winding having connected the main stator winding forming the exciting circuit of the motor, a with the mains. working winding 0n the rotor provided with I FRIEDRICH KADE. 

